An old post revisited. Not to glorify my previous research, but rather to get up the stand and to tell the 'woops, I got it all wrong' story
And who told me I was wrong? Well, August Weiss did, actually. In 1962.
So what did we learn in the mean time:
-Fred Datig 'borrowed' the picture from Gerhard Bock's publication 'Moderne Faustfeuerwaffen und ihr Gebrauch', 3rd edition, published in 1942.
-Unlike Datig, Bock took the trouble to give the proper names of the men pictured and Weiss was kindly enough to point out one of the men and refer to the picture in Bock's book in a letter dating from 1962.
With kind cooperation of Martin Krause (Sauerfan) who provided me with a scan of the page in question, it is now possible to identify the men on the picture, and this time properly:
From left to right:
Georg Luger Senior.
R. Tschoepke.
The cardboard target
and sitting in front of it is Baurat (title) Meyer.
Prof. Rauch.
Heinrich Hoffmann.
Georg Luger Junior.
...well, at least I got some of them right initially (Junior, Senior and Hugo Boardcard aka the target)